JP4721014B2 - Piston of internal combustion engine - Google Patents

Description

  The present invention relates to a piston of an internal combustion engine, and more particularly to a piston in which a piston body and a pin support member are formed separately.

The piston of an internal combustion engine has a problem that a secondary movement of the piston occurs around the piston pin position in the vicinity of the top dead center, and a slap sound or the like is generated when the piston collides with the cylinder wall surface.
Also, particularly during the expansion stroke, when the piston is pressed by the combustion pressure, side force is generated according to the angle with the connecting rod, and this causes friction between one side of the piston, the so-called thrust side, and the cylinder wall surface. There is a problem of rising.

For such problems, it is effective to suppress the secondary motion and side force by moving the piston rod position closer to the center of gravity of the piston and increasing the length of the connecting rod so as to reduce the angle with the connecting rod. It is.
However, since the center of gravity of the piston is located on the top surface side, a compression ring groove, an oil ring groove, etc. are formed on the top surface side of the piston. It is difficult to form a pin hole.

Therefore, a technique has been developed in which a pin support member having a pin hole is formed separately from the piston body, and the piston pin position is brought closer to the top surface side by assembling the pin support member in the piston body.
For example, a piston having a structure in which a pin pivot member (pin support member) is fitted into the piston body, and a fixed portion of the pin pivot member is fixed to a fixed seat surface of the piston body with a fixing bolt is disclosed ( (See Patent Document 1)
Japanese Patent Laid-Open No. 10-292863

However, the technique disclosed in Patent Document 1 is configured such that the fixing bolt is inserted into the bolt insertion hole from the head side (top surface side) of the piston body and fastened with a nut from the top surface rear side. Such a configuration having an insertion hole penetrating the top surface of the piston is not preferable because it reduces the strength and durability of the piston.
Further, in Patent Document 1, the piston pin is supported by a half-pinned pin pivot hole formed on the back surface of the piston top surface and a pin pivot member corresponding to the half-pin pin pivot hole. However, there is a problem that when the pin support hole for supporting the piston pin is divided as described above, high-precision molding is required in consideration of thermal deformation of the piston body.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide an internal combustion engine capable of ensuring the piston strength and durability while bringing the piston pin position close to the top surface. To provide a piston.

In order to achieve the above object, the piston of the internal combustion engine according to claim 1 is a piston that strokes in a cylinder of the internal combustion engine and has a substantially cylindrical shape having a top surface, and a thrust on the back surface of the top surface. A support base portion that protrudes toward the bottom dead center side in the stroke direction is formed at the side and anti-thrust side positions, and the screw hole that allows the screw portion of the bolt to be screwed onto the bottom dead center side surface of the support base portion The piston body has a pin hole that pivotally supports the end of the piston pin, and the thrust side and anti-thrust side surfaces are spaced apart from the support base, while the stroke side top dead center side surface is A main body that contacts the back surface of the top surface of the piston body, and extends from the main body to both sides in the thrust direction. One top dead center surface is the thrust side, and the other top dead center surface is the anti-thrust side. In contact with the bottom dead center side surface of the support base of Each of the bolts has a pair of support arm portions with through-holes through which the threaded portions of the bolts can pass, and the threaded portions of the bolts pass through the through-holes of the support arm portions and are screwed into the screw holes of the piston body. Thus, a pin support member fastened to the piston main body is provided, and the pin support member is configured separately at one end side and the other end side of the piston pin .

The piston 請 Motomeko 2 of the internal combustion engine, Oite to claim 1, between the back and the pin stroke direction improvement dead point side surface of the main body portion of the supporting member of the top surface of the piston body, and the A shim is interposed between at least one of the bottom dead center side surface of the support base portion of the piston body and the top dead center side surface of the support arm portion of the pin support member. .

According to the piston of the internal combustion engine of the first aspect of the present invention using the above means, the formation of the oil groove and the piston pin support position interfere with each other by forming the piston body and the pin support member separately. The piston pin can be positioned on the top surface side without being restricted. Thereby, noises such as slap sounds and friction can be reduced.
Since the pin support member that supports the piston pin is fixed in contact with the piston body at three points of the main body and the support arm, the force transmitted from the piston body to the pin support member is sufficiently dispersed. The strength and durability of the piston can be improved. In addition, the thrust side and anti-thrust side surfaces of the main portion of the pin support member are provided at a distance from the support base, thereby affecting the influence of thermal deformation or molding error in the thrust direction of the piston support member. Can be reduced.

Furthermore , weight reduction of a pin support member can be achieved by making a pin support member into a different body.
According to the piston of the internal combustion engine of claim 2 , the shim is interposed between at least one of the back surface of the top surface of the piston body and the main portion of the pin support member and between the support base and the support arm. By doing so, the distance between the piston main body and the pin support member caused by thermal deformation, molding error, etc. can be adjusted by the shim, and a configuration in which the abutment is surely made at three points can be achieved.

  As a result, the pin support member can be securely fixed to the piston body without rattling or the like, and noise can be reduced and the strength and durability can be further improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIGS. 1 to 8, FIG. 1 is an exploded perspective view of a piston of an internal combustion engine according to the present invention, and FIGS. 2 to 5 are a perspective view, a front view, a bottom view, and a sectional view of a piston body. 6 to 8 are a perspective view, a bottom view, and a front view of the piston bracket, respectively. Hereinafter, description will be made based on these drawings.

As shown in FIG. 1, the piston 1 is a piston that strokes in a cylinder of an internal combustion engine (not shown) via a connecting rod 2.
The piston 1 includes a piston body 10 and a pair of piston brackets 14 and 14 (pin support members) that pivotally support a piston pin 12 formed separately. The piston brackets 14 and 14 are fastened in the piston body 10 by bolts 18, 18, 18, and 18 with shims 16, 16, 16 ′, 16 ′, 16 ′, and 16 ′ interposed therebetween. It is fixed by that. Hereinafter, the top dead center side in the stroke direction of the piston 1 is the upper side, the lower dead center side is the lower side, and the axial direction of the piston pin 12 orthogonal to the vertical direction is perpendicular to the pin direction, and further to the vertical direction and the pin direction. The direction will be described as the thrust direction. In the thrust direction, the side on which the piston body 10 is pressed against the cylinder wall surface in response to the side force generated according to the angle with the connecting rod during the expansion stroke is the thrust side, and the opposite side is the anti-thrust side.

As shown in FIGS. 2 to 5, the piston body 10 has a substantially cylindrical shape in which the ring land portion 22, the skirt portions 24 a and 24 b, and the sidewall portions 26 and 26 extend downward from the crown portion 20 forming the top surface. ing.
The crown portion 20 has a circular shape in plan view, and the ring land portion 22 extends in a cylindrical shape downward from the periphery of the crown portion 20.

A top ring groove 30, a second ring groove 32, and an oil groove 34 extending in the circumferential direction are arranged in parallel at predetermined intervals on the outer peripheral surface of the ring land portion 22. Note that a portion directly below the oil groove 34 forms the lower end of the ring land portion 22.
The top ring groove 30, the second ring groove 32, and the oil groove 34 are provided with a top compression ring, a second compression ring, and an oil ring (not shown). The oil groove 34 is provided with a plurality of oil holes 36 penetrating to the inside of the piston body 10.

The skirt portions 24 a and 24 b are formed to extend downward from the outer peripheral surface of the ring land portion 22 on the thrust side and the anti-thrust side.
The sidewall portions 26, 26 extend from the lower surface of both side portions in the pin direction of the ring land portion 22 so as to be connected to the side end portions in the circumferential direction of the skirt portions 24 a, 24 b in the thrust direction. And the said side wall parts 26 and 26 have comprised the shape opened in the thrust direction center part, expanding toward the downward direction from the ring land part 22 vicinity.

That is, the sidewall portions 26, 26 are connected portions 40a, 40a, 40b, 40b inclined in the upward direction toward the thrust direction center side from the connection portions with the circumferential side end portions of the skirt portions 24a, 24b and the thrust direction center. In the part, it is formed of central portions 42 and 42 having a predetermined thickness in the vertical direction and parallel to the lower end of the ring land portion 22.
Further, on the back surface of the crown portion 20, that is, the piston body inner upper surface 50, support base portions 52, 52, 52, 52 projecting downward are formed at both end positions in the pin direction on the thrust side and the anti-thrust side, respectively. Yes. Specifically, as shown in FIG. 4, the support bases 52, 52, 52, 52 are respectively located at the four corners located at the boundary between the skirts 24 a, 24 b and the sidewalls 26, 26 in the bottom view. It has a shape that bulges from the peripheral surface toward the center. Further, as shown in FIG. 5, bottomed screw holes 54, 54, 54, 54 to which the bolts 18 can be screwed are formed on the lower surfaces of the support base parts 52, 52, 52, 52, respectively. Yes.

Further, the piston body inner upper surface 50 excluding the support bases 52, 52, 52, 52 has a cross shape in a bottom view, and forms a horizontal plane in a part or the entire surface in the pin direction.
On the other hand, as shown in FIGS. 6 to 8, the piston bracket 14 is composed of a main part 62 provided with a pin hole 60 that pivotally supports one end of the piston pin 12 and a pair extending from the main part 62 in the thrust direction. Support arm portions 64 and 64. Although only one piston bracket 14 is shown in FIGS. 6 to 8, the other piston bracket 14 has the same configuration.

The main body 62 has a horizontal surface on the upper surface and a smoothly curved shape along the shape of the pin hole 60 on the lower surface. The length in the thrust direction of the main body 62 is smaller than the distance between the thrust-side support bases 52 and 52 and the anti-thrust-side support bases 52 and 52 of the piston body inner upper surface 50. .
The support arm portions 64, 64 extend from the lower portions of both side surfaces of the main body portion 62 to both sides in the thrust direction along the lower surface, and are formed such that the outer surface approaches the inner surface as viewed from the bottom when viewed from below. . Further, through holes 66 and 66 are formed in the end portions of the support arm portions 64 and 64 so as to penetrate the screw portion 18a of the bolt 18 in the vertical direction so that the screw portion 18a can penetrate therethrough.

The shims 16 and 16 are plate members interposed between the upper surfaces of the main portions 62 and 62 of the piston brackets 14 and 14 and the piston main body inner upper surface 50 when assembled. The shims 16 and 16 have a larger area than the upper surfaces of the main portions 62 and 62 of the piston brackets 14 and 14, and the material of each shim is a metal such as stainless steel.
In addition to the shim 16, the shims 16 ', 16', 16 'are respectively disposed between the support base portions 52, 52, 52, 52 on the back side of the piston body and the piston bracket support arm portions 64, 64, 64, 64. , 16 'are interposed. FIG. 16 shows a perspective view of the shim. As shown in FIG. 16, the shims 16 ′, 16 ′, 16 ′, and 16 ′ have a washer shape made of metal such as stainless steel. As shown in FIGS. 14 and 15, the piston 1 may be configured such that the shim 16 and any one of the shims 16 ′, 16 ′, 16 ′, and 16 ′ are interposed.

Hereinafter, the configuration of the piston 1 in a state where the piston main body 10 and the piston brackets 14 and 14 configured as described above are assembled will be described.
Referring to FIGS. 9 to 13, there are shown a perspective view, a front view, a bottom view, and a cross-sectional view in the piston assembly state.
In the piston assembled state, the end portions of the cylindrical piston pins 12 are inserted into the pin holes 60 and 60 of the piston brackets 14 and 14, respectively, and are pivotally supported. The central portion of the piston pin 12 is pivotally supported at one end of the connecting rod 2, and the piston brackets 14 and 14 are disposed so as to sandwich the connecting rod 2.

  The screw portions 18a, 18a, 18a, 18a of the bolts 18, 18, 18, 18 pass through the through holes 66, 66, 66, 66 of the piston brackets 14, 14, respectively, and the support base portion 52 of the piston body 10; 52, 52, 52 are screwed into the screw holes 54, 54, 54, 54, and the heads 18b, 18b, 18b, 18b of the bolts 18, 18, 18, 18 and the support base 52 of the piston body 10 are provided. The piston brackets 14 and 14 are fastened to the piston main body 10 between the pistons 52, 52 and 52.

  By fastening the piston brackets 14, 14 and the piston body 10, the piston body inner upper surface 50 and the main parts 62, 62 upper surfaces of the piston brackets 14, 14 come into contact with each other, and the support base 52 of the piston body 10, 52, 52, 52 and the support arm portions 64, 64, 64, 64 of the piston brackets 14, 14 come into contact with each other. And, at least one of shims 16, 16 and shims 16 ', 16', 16 ', 16' is interposed in the contact portion. That is, the piston brackets 14 and 14 are in contact with the piston body 10 at three points.

Further, the side surfaces of the upper portions of the support portions 64, 64, 64, 64 of the main body portions 62, 62 of the piston brackets 14, 14 are in the thrust direction with the support base portions 52, 52, 52, 52 of the adjacent piston body 10. At a predetermined interval.
In the assembled state, the axial center of the piston pin 12 is slightly offset toward the thrust side in the thrust direction from the diameter center of the top surface of the piston 1. Thereby, a force in the anti-thrust direction can be generated in the piston 1 during the expansion stroke, and the side force can be reduced.

As described above, the piston brackets 14 and 14 are in contact with the support arm portions 64, 64, 64 and 64 and the upper surfaces of the main body portions 62 and 62, respectively. Can be sufficiently dispersed, and the strength and durability of the piston 1 can be improved.
In addition, by configuring the piston brackets 14 and 14 separately, it is possible to reduce the size and weight of the piston brackets 14 and 14 as much as parts that connect the support arm portions 64 and 64 are not necessary as compared with the integrally configured bracket.

  Further, shims 16, 16, piston bracket support arm portions 64, 64, 64, 64 and a support base portion 52 on the back side of the piston main body are provided between the upper surfaces of the main portions 62, 62 of the piston brackets 14, 14, and the inner upper surface 50 of the piston main body. , 52, 52, 52, the shims 16 ′, 16 ′, 16 ′, 16 ′ are interposed between the piston main body 10 and the piston brackets 14, 14 caused by thermal deformation or molding error. The interval can be adjusted by the shims 16 and 16 or the shims 16 ′, 16 ′, 16 ′, and 16 ′, and a configuration in which the gaps are reliably brought into contact at three points can be obtained. Further, since the side surfaces of the main portions 62, 62 of the piston brackets 14, 14 have a predetermined distance from the support base portions 52, 52, 52, 52 of the adjacent piston body 10, thermal deformation in the thrust direction or The influence of molding error and the like can be reduced.

Thereby, the piston brackets 14 and 14 can be securely fixed to the piston body 10 without rattling or the like, and noise can be reduced and the strength and durability can be further improved.
The piston 1 has the piston body 10 and the piston brackets 14 and 14 formed separately, so that the piston pin 12 can be moved without any restriction such as interference between the oil groove forming position and the piston pin supporting position. It can be located on the top side. As a result, the center of gravity of the piston 1 and the center of the piston pin 12 are brought close to each other, so that the piston 1 can be reduced in size and weight, and the inertial moment at the time of stroke can be reduced by reducing the center of gravity of the piston 1. Therefore, noise such as slap noise can be reduced. Furthermore, by lowering the center of gravity of the piston 1, the connecting rod 2 can be lengthened and the connection ratio can be increased, so that side force and friction can be reduced.

Thus, in the piston of the internal combustion engine according to the present invention, it is possible to ensure the strength and durability of the piston 1 while bringing the position of the piston pin 12 close to the top surface side.
Although the description of the embodiment of the piston of the internal combustion engine according to the present invention has been completed above, the embodiment is not limited to the above embodiment.
For example, in the above embodiment, the shims 16 and 16 are made of stainless steel, but the shim material is not limited to this.

In the above-described embodiment, the piston brackets 14 and 14 are configured separately from each other. However, the piston bracket is not limited to a separate one. For example, the support arms of the piston bracket are mutually connected in the pin direction. It does not matter even if it is connected and integrated.
Moreover, in the said embodiment, although the support base parts 52, 52, 52, 52 of the piston main body 10 are independently formed in four places, a support base part is not restricted to such a structure, for example, The thrust side support base portions and the anti-thrust side support base portions may be connected in the pin direction to form a pair of support base portions.

Moreover, in the said embodiment, although the piston pin 12 is the structure offset to the thrust side, it is not restricted to the structure especially offset in this way.
In the above embodiment, the shim 16 is a plate member, and the shim 16 'is a washer shape. However, the shape of the shim is not limited to this, and for example, the shim 16' is supported on the back side of the piston body. A shape that matches the shape of the lower surface of the part may be used.

It is a disassembled perspective view of the piston of the internal combustion engine which concerns on this invention. It is a perspective view of a piston main body. It is a front view of a piston main body. It is a bottom view of a piston main body. It is sectional drawing which follows the AA line of FIG. It is a perspective view of a piston bracket. It is a front view of a piston bracket. It is a bottom view of a piston bracket. It is a perspective view in a piston assembly state. It is a perspective view in a piston assembly state. It is a front view in a piston assembly state. It is a bottom view in a piston assembly state. It is sectional drawing which follows the BB line of FIG. It is sectional drawing which shows the other example in a piston assembly state. It is sectional drawing which shows the other example in a piston assembly state. It is a perspective view of a shim.

Explanation of symbols

1 Piston 10 Piston Body 12 Piston Pin 14 Piston Bracket (Pin Support Member)
16, 16 'Shim 18 Bolt 20 Crown part 22 Ring land part 24a, 24b Skirt part 26 Side wall part 50 Inner upper surface of piston main body 52 Support base part 54 Screw hole 60 Pin hole 62 Main part 64 Support arm part 66 Through hole

Claims (2)

A piston that strokes in a cylinder of an internal combustion engine,
A substantially cylindrical shape having a top surface is formed, and a support base portion protruding toward the bottom dead center side in the stroke direction is formed at the thrust side and anti-thrust side positions on the back surface of the top surface, and below the support base portion A piston body having a screw hole into which a screw portion of a bolt can be screwed on a surface on the dead center side;
It has a pin hole that pivotally supports the end of the piston pin, the thrust side and the side opposite to the thrust side are spaced from the support base, and the top dead center side surface in the stroke direction is the top surface of the piston body A main body portion that contacts the back surface of the support base, and the support base portion that extends from the main body portion to both sides in the thrust direction, wherein one top dead center side surface is the thrust side and the other top dead center surface is the anti-thrust side. A pair of support arm portions that contact the bottom dead center surface and have through-holes through which the thread portions of the bolts can pass, and the thread portions of the bolts pass through the through-holes of the support arm portions; A pin support member fastened to the piston body by screwing into the screw hole of the piston body;
The piston of the internal combustion engine, wherein the pin support member is configured separately on one end side and the other end side of the piston pin .   Between the back surface of the top surface of the piston body and the surface of the main part of the pin support member in the stroke direction top dead center side, and the bottom dead center side surface of the support base part of the piston body and the pin support member 2. A piston for an internal combustion engine according to claim 1, wherein a shim is interposed in at least one of the support arm portion and the top dead center side surface.

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